Conventionally, optical devices have not been designed for use in modular systems. Therefore such optical devices are housed in a conventional manner in a housing which is designed to remain in one location, and which provides suitable electromagnetic shielding to prevent emissions from an optical device interfering with external devices and equipment.
However, a requirement for flexible modular optical equipment introduces a requirement for an optical device module which provides the required electromagnetic shielding capability for modules which may be inserted and removed from modular equipment racks. Since during normal operation the modules may reach temperatures of up to 85 degrees centigrade, the module should provide adequate thermal insulation as well as electromagnetic shielding so that modules may be inserted and removed without powering down the equipment rack, and waiting for the module to be removed to cool down.
It will be appreciated that the above requirements are conflicting because electromagnetic shielding is usually provided using a material which is electrically conductive, which in general, means that the material is also thermally conductive. So the required thermal insulation will not be achieved.